Conventionally, in order to make it smaller and lighter and to realize less maintenance, a power converter provided in a railway vehicle uses a traveling-wind cooling approach that blows a traveling wind to heat dissipating fins of a cooling body so as to perform cooling, wherein the cooling body cools a power unit constituted of, for example, a semiconductor element and the traveling wind is generated due to a vehicle traveling.
FIG. 1 illustrates an exemplary configuration of a cooler of a power converter disclosed in Patent Document 1 below, wherein a baffle plate 20 having a mountain-shaped cross section is provided inside a protection cover 19 of a cooler 1 and openings are provided in the protection cover 19 as appropriate so as to intake cooling air (see the curved arrows) from the openings.
A cooler 1u situated in the middle of a plurality of coolers 1 that are arranged side by side is smaller than the adjacent coolers 1 situated on both sides of the cooler 1u (the height of its heat dissipating fins is smaller), wherein the height of heat dissipating fins of the cooler 1u situated in the middle portion is made smaller than the heights of heat dissipating fins situated in the other portion, along the convexity of the baffle plate 20 having a mountain-shaped cross section and being provided inside the protection cover 19.
Such a configuration makes it possible to perform a traveling-wind cooling using a last cooler 1 efficiently because the baffle plate 20 is oriented (slopes) appropriately with respect to the last cooler 1 such that a wind from the left direction (illustrated), that is, a wind from the traveling direction (a traveling wind) is directed to the last cooler 1 situated in a position where it is most difficult for the traveling wind to reach and because the cooler 1u situated just before the last cooler 1u is smaller (the height of its heat dissipating fins is smaller), so the traveling wind whose direction has been changed due to the slope of the baffle plate 20 can easily enter into the last cooler 1.
FIGS. 2A to 2C and 3 are diagrams that illustrate a cooling structure of a power converter for a railroad vehicle disclosed in Patent Document 2 below, wherein a plurality of semiconductor modules 2 that constitute a power unit are thermally conductively placed on the upper surface of a planar substrate (a heat receiving plate) 11 of a cooling body 1, and a plurality of thin planar heat dissipating fins 12 are installed parallel to one another on its lower surface at a predetermined spacing, the substrate being made of highly heat-conductive material.
FIG. 3 illustrates a structure of a fin holding plate described in FIGS. 2A and 2C, and in FIG. 3, a fin holding plate 33 is provided with convexities 33b that each enter into a space between two heat dissipating fins of the cooling body, wherein the fin holding plate 33 has slopes at both end portions situated in a front and rear in a vehicle traveling direction, and its central portion has a trapezoidal shape.
In the example of FIGS. 2A to 2C, the planar fin holding plate 33 is provided across the ends of the heat dissipating fins 12 of the cooling body 1 (in the lower end portion in FIG. 2B) in a width direction of the substrate 11 (in the vertical direction in FIG. 2A) and is coupled to the heat dissipating fins 12 by, for example, brazing, so as to bring together all of the heat dissipating fins.
For example, as can be seen from FIG. 3, when the fin holding plate 33 is coupled to the ends of the heat dissipating fins 12, each of the ends of the heat dissipating fins 12 is partially inserted into a slit 33c between two convexities 33b of the fin holding plate 33 and attached to a flat portion 33a, and the attached portions are coupled by, for example, metal brazing, so as to bring together a plurality of heat dissipating fins 12 using the fin holding plate 33.
As illustrated in FIG. 2B, a fin holding plate 33 is provided at each of the following three points: at the front end, in the middle, and at the rear end in a length direction of the heat dissipating fins 12 (in a travelling-wind flowing direction).
When the ends of the heat dissipating fins 12 are brought together using the fin holding plates 33, a wind adjusting effect is produced due to the fin holding plates 33 being situated side by side in the traveling-wind flowing direction.
Specifically, each of the fin holding plates 33 prevents a traveling wind generated due to a vehicle traveling from flowing out to outside the heat dissipating fins, and the traveling wind flows with its flow rate being increased due to the convexities 33b of the fin holding plate 33.
The traveling wind flowing outside the heat dissipating fins 12 is intaken into spaces between the heat dissipating fins from between the fin holding plates 33 at the front end and in the middle and from between the fin holding plates 33 in the middle and at the rear end, so as to flow between the heat dissipating fins, which makes it possible to provide a cooling effect more uniformly throughout the entire length of the substrate 11 of the cooling body 1 and to prevent an increase in the temperature in a position downstream of a traveling wind (on the rear-end side) in the substrate 11.
There has been a problem in which, in the technology disclosed in Patent Document 1 above, an internal flow resistance is increased due to the protection cover, which results in difficulty in intaking sufficient cooling air.
Further, there has been a problem in which the technology disclosed in Patent Document 2 above permits an intake of cooling air through a fin holding plate so as to provide a cooling effect uniformly, but it is not possible to intake a traveling wind between the fins while traveling at a low speed, which results in not obtaining a sufficient cooling effect.
Patent Document 1: Japanese Patent No. 3469475 (FIG. 21)
Patent Document 2: Japanese Laid-open Patent Publication No. 2007-134471 (FIGS. 9 and 10)